A large number of substantially water insoluble biocidal and agrochemical active substances are used extensively for controlling pests and/or for promoting the healthy growth of crops and livestock. For this purpose it is usually necessary or preferred to apply them in a fluid and preferably a diluted form exhibiting a viscosity sufficient to remain as droplets on the leaves in order to penetrate, but not too high that spraying becomes difficult.
Reference is made for example to WO 95/005402 A1 assigned to BASF disclosing aqueous copolymer dispersions are obtained by radical initiated copolymerisation or by copolymerisation initiated by the use of ionising radiation of: (A) 40 to 99% by weight of one or several water-insoluble, monoethylenically unsaturated monomers; (B) 1 to 60% by weight of one or several water-soluble, monoethylenically unsaturated monomers; and (C) 0 to 30% by weight of one or several ethylenically polyunsaturated monomers, in an aqueous medium in the presence of 2 to 20% by weight, in relation to the total monomer amount, of surface active compounds as emulsifiers. These dispersions have a mean particle size from 5 to 37 nm as determined by light scattering in the aqueous medium. Such dispersions are suitable for preparing varnishes, paints and adhesives, as film-builders in hair-care cosmetic compositions, as protective media against ultraviolet light and as carriers for substances contained in pharmaceuticals, cosmetics or agrochemicals. The document, however, does not disclose the use of polyacrylates for increasing the viscosity of compositions comprising biocides and oil bodies.
A major issue for pesticides dispersions in oil carriers is the stability of the formulation during storage: pesticides particles tend to settle and separate over time and/or temperature variations leading to non homogeneous products. The pesticide formulation should therefore exhibit a moderate viscosity of about 500 to about 1000 mPa·s to prevent settling during storage but also should become rather fluid when submitted to mechanical energy (mixing, stress . . . ) for a better handling by the end-users. To obtain such defined viscosity behaviour the use of rheology modifiers is necessary.
The object of the present invention has been to design new rheology modifiers able to provide the appropriate rheological behaviour to oil-based biocide compositions.